Several skin conditions are associated with the overproduction or unwanted production of melanin the skin, including age spots, freckles, and liver spots. The synthesis of melanin occurs in melanocyte cells in the skin and is a complex process involving several biochemical pathways. Some skin lighteners or depigmenting agents, such as hydroquinone and kojic acid, act as inhibitors of tyrosinase, an enzyme that has its catalytically active domain within organelles known as melanosomes. Tyrosinase converts phenols, including tyrosine, to ortho-quinones which are subsequently converted to melanin within the melanosomes. Other skin lighteners, such as serine-protease inhibitors, act by disrupting the transfer of the melanosomes from melanocytes to the keratinocytes where melanin is deposited.
While skin lighteners such as hydroquinone and kojic acid have found some utility in cosmetic and dermatological products, there remains a continuing need for products that effectively reduce pigmentation of skin. It is therefore an object of the invention to provide compositions and methods for reducing pigmentation in human skin, including, for example, treatment of hyperpigmentation, unwanted pigmentation, age spots, liver spots, freckles, and the like. The foregoing discussion is presented solely to provide a better understanding of nature of the problems confronting the art and should not be construed in any way as an admission as to prior art nor should the citation of any reference herein be construed as an admission that such reference constitutes “prior art” to the instant application.